1. Technical Field
Various embodiments of the present invention relate to a control device, a power receiving device, an electronic apparatus, a contactless power transmission system, and the like.
2. Related Art
In recent years, much attention has been paid to contactless power transmission (wireless power transfer) in which electromagnetic induction is used to make power transmission possible without a metal contact. Power supply to electronic apparatuses such as a household appliance, a mobile terminal, and an electric car has been proposed as an application example of the contactless power transmission.
A known technology for the contactless power transmission is disclosed in JP-A-2010-213414, for example. In the known technology, in a waiting period in which landing of a power receiving device is waited for, a power transmitting device intermittently transmits power to the power receiving device. Also, a method is adopted in which the transmitting power to the power receiving device in the period of intermittent power transmission for landing detection is reduced compared with the power in a normal power transmission.
In the case where the distance between a power transmitting device and a power receiving device (distance between a primary coil and a secondary coil) is large in a contactless power transmission system, a drive voltage for transmitting power (primary coil drive voltage) of the power transmitting device needs to be set high in order to realize appropriate landing detection.
However, when the drive voltage is set high, in the case where the distance between the power transmitting device and the power receiving device is reduced in this state, the output voltage of a power receiving portion of the power receiving device becomes higher than an allowable voltage, and a failure may occur in a circuit of the power receiving device. Specifically, the output voltage, which is a rectified voltage, increases, and thus a breakdown voltage abnormality in which the output voltage exceeds a breakdown voltage of a transistor that constitutes the circuit, or the like occurs. Therefore, there is a problem in that a landing detection over a large distance range cannot be realized.